Planetary-gear printer for data-processing equipment



A. C. TRAB Jan. 20, 1970 PLANETARYGEAR PRINTER FOR DATA-PROCESSINGEQUIPMENT 2 Sheets-Sheet 1 Filed Feb. 8. 1968 KOPQMJMm m r 0 mm INVENTOR. ABDUL RA HIM CHEIKH TRAB A. C. TRAB Jan. 20, 1970 PLANETARY-GEAR PRINTER FOR DATA-PROCESSING EQUIPMENT 2 Sheets-Sheet 3 Filed Feb. 8, 1968 INVENTOR. ABDULRAHlM CHEIKH TRAB United States Patent US. Cl. 10192 11 Claims ABSTRACT OF THE DISCLOSURE In a fixed cylindrical housing, open at one side toward a printing platen, a shaft parallel to the housing axis revolves about the latter and rotatably supports a set of pinions meshing with respective ring gears which are centered on the housing axis and independently rotatable therearound. Disks coaxial with the housing are coupled with the shaft for joint rotation about the axis with frictional engagement of respective ring gears to drive them in a predetermined direction. In a printing position occurring once per shaft revolution, in which each pinion confronts the open housing side, a digit wheel rigid with the pinion extends any one of several type faces on its periphery into contact with the platen if the corresponding ring gear occupies one of several offnormal positions in which it can be selectively arrested. A releasable detent normally holds this ring gear in a home position in which a blank portion of the wheel periphery advances toward the platen.

My present invention relates to a high-speed printer as used, for example, in data-processing equipment to record numerical information in a multiplicity of digital columns.

In commonly assigned application Ser. No. 679,037, filed by me jointly with Heinz Ricke on Oct. 19, 1967, there has been disclosed a printer of this general type wherein a cylindrical platen performs a cycloidal motion parallel to itself toward a printing roller carrying a plurality of digit wheels. It has also already been proposed to move a printing roller in a similar manner toward and away from a platen, e.g. as described in US. Patent 2,910,936 or in Swiss Patents No. 232,781, and No. 387,993. Systems of the latter type, however, are quite complex and, as a rule, operate at relatively low speeds since the planetary-gear system designed to generate the cycloidal motion must be stepped through a number of successive cycles in order to align a desired digit with the printing platen.

The general object of my present invention is to provide a simplified system of this character in which the aforestated drawback is avoided.

A more particular object of this invention is to provide means in such system for the selection of a desired type face with the aid of a continuously operating planetarygear device.

It is also an object of my invention to provide means for positively insuring simultaneous printing of digits or other characters in a plurality of juxtaposed printing stages (e.g. printing zones associated with different decadic positions) to allow for the continuous feeding of a paper or other information carrier without mutually disaligning the characters of a given line.

These objects are realized, pursuant to my present invention, by the provision of a planetary drive including a ring gear in mesh with a pinion, the latter being supported by a planet carrier for revolution about an axis while rolling on the inner periphery of the ring gear. The

3,490,364 Patented Jan. 20, 1970 pinion is rigid and coaxial with a printing wheel which, once per revolution, approaches a printing platen disposed adjacent the planet carrier whereby one of several type faces carried on the outer periphery of the wheel marks a sheet interposed between the wheel and the platen. To select the type face which is to make the print, I further provide means for orienting the ring gear in dilferent angular positions with consequent shifts in the position of the printing wheel at the instant of advance toward the platen, this advance occurring invariably in a position of closest approach of the planet carrier to the platen so that printing always takes place at a predetermined point of a cycle regardless of the selected orientation of the ring gear. As a result, all the printing wheels mounted on a common planet carrier operate simultaneously to place their selected type faces (or a blank portion of their periphery) in contact with a message sheet adjoining the platen.

Pursuant to still another feature of this invention, I provide a frictional coupling between the planet carrier and the ring gear whereby the latter can be repositioned, in accordance with the selected type face, in response to the torque applied by the driving mechanism for the planet carrier; this dispenses with the need for a separate power source for the wheel adjustment.

In order that the complete range of type faces (usually 10) be available for selection during any revolution of the planet carrier, the teeth of the ring gear and the pinion should have a simple numeral ratio n:m wherein n and m are integers, with m preferably not greater than 2. The pinion, and with it the printing wheel, then rotates through Zmr/m. radians during each revolution of the planet carrier; if the periphery of the printing wheel is divided into m segments carrying identical sets or groups of type faces, then the machine will print the same kind of character during consecutive revolutions in which the position of the ring gear remains unchanged or, in certain positions of this ring gear, will not print anything as the platen is confronted by blank zones separating these sets of type faces.

Thus, a very effective arrangement according to the invention utilizes a tooth ratio of 3:2, the printing wheel carrying two identical sets of type faces with a 180 oifsetbetween identical characters. Either of the two blank zones between these sets periodically confronts the platen in any of three home positions of the ring gear spaced apart. A releasable detent arrests the ring gear in any of these home positions against frictional rotary entrainment by the planet carrier, more specifically by a disk centered on the axis of revolution which coincides with the axis of the ring gear. When the detent is released, the ring gear begins to rotate until a projection thereon strikes a stop interposed in its path in a selected position which corresponds to the desired type face to be made effective; the ring gear is subsequently allowed to proceed to its next home position whereupon the procedure will be repeated with the other set of type faces.

The invention will be described in greater detail with reference to the accompanying drawing in which:

FIG. 1 is a side-elevational view (parts broken of a printer according to the invention; and

FIG. 2 is a cross-sectional viewztaken on the line 11-11 of FIG. 1.

The machine shown in the drawing comprises a cylindrical housing 1 with a lateral opening 12 confronting a printing platen 11; housing 1 has a pair of end flanges 1, 1" in which two gudgeons 13', 13" are rotatably journaled by means of ball bearings 26, these gudgeons being rigid with an eccentric shaft 3 lying parallel to the housing axis 0. Shaft 3 has a keyway 14 receiving keys 15 of a plurality of axially spaced disks 4 which are centered on axis 0 and rotate in unison with gudgeons 13',

away) 13"; the first one of these disks, designated 4a, has an extended hub fastened to shaft 3 by a pin 15a. Each disk 4, 4a rotatably supports a respective ring gear 5 with which it is frictionally coupled by means of a substantially noiseless torque-transmitting element 6 here shown as a corrugated spring washer.

Ring gear 5 has an inner set of teeth 5' in mesh with the teeth 7 of a pinion or planet gear 7 which is freely rotatable on the shaft 3, revolving in a planetary orbit P about axis during each revolution of the planet carrier 3. A printing wheel 8 coaxial and rigid with pinion 7 (e.g. press-fitted thereon) carries two sets of type faces 8A, 8B at diametrically opposite locations, these sets being separated by blank zones 8C and 8D. Ring gear also has three external projections 5A, 5B, 5C engageable by a detent 9 in the form of an arm on a shaft 16 which is normally held by a spring 17 against a stop 18 so that the arm 9 occupies the blocking position illustrated in FIG. 2; in the specific position shown in this figure, projections 5A rests against the arm 9 as the ring 5 tends to follow the counterclockwise rotation (arrow A) of the associated disk 4 coupled with planet carrier 3.

A set of solenoids are selectively operable to extend their cores into the path of projections 5A, 5B, 5C so as to arrest the ring gear 5 in any of 10 different working positions upon its release from one of its three home positions defined by the engagement of arm 9 with any of projections 5A, 5B, 5C. As best seen in FIG. 2, pinion 7 has a diameter and therefore a tooth ratio equal to twothirds that of the inner periphery of ring gear 5 so that this pinion, together with wheel 8, rotates through 540 during each revolution of shaft 3 if the ring gear 5 remains stationary. With shaft 3 positioned at the zenith of its orbit P, i.e. the point proximal to the open side 12 of housing 1, blank zone 8C lies closest to platen 11 so that nothing is printed on a paper sheet 19 interposed between the platen and housing 1. If the position of ring gear 5 remains unchanged during the next revolution, blank zone 8D will next confront the platen 11 so that again no printing takes place.

When it is desired to print a character carried on one of the type faces of each group 8A, 8B, detent'arrn 9 is swung out of the way of projection A (arrow B in FIG. 2) and one of the solenoids 10 is energized to arrest the next projection, here the lugs 5B, in a position in which the desired type face will be aligned with platen 11 at the instant when the pinion 7 again returns to the zenith. The selected type face then performs a cycloidal motion through the longitudinal housing slot 12, this motion being radially oriented at the moment of contact with sheet 19. Since such contact is only instantaneous, the cylindrical platen 11 may be con tinuously rotated (arrow C) to advance the sheet 19 from one line of print to the next, in synchronism with the rotation of shaft 13, 3, 13".

Inasmuch as the repositioning of ring gear 5 requires less than half a revolution of shaft 3, it may be initiated by the withdrawal of detent arm 9 in approximately the nadir position thereof, thus after a swing of about 180 from the printing position shown in FIG. 2. Following the next' printing operation, the extended solenoid core may be retracted after a rotation of only a few degrees whereupon the previously released detent arm intercepts the next projection (e.g. 5B) in time for allowing another selection to be made within the same orbital revolution. This sequence of operations may be controlled by a timer 20, FIG. 1, which operates a solenoid 21 for the tripping of arm 9 and also opens a gate 22 through which energizing voltages are applied, once per revolution, to the solenoid leads 23 of the several digital stages from a selector 24. The latter is representative of a variety of manual or automatic devices for registering combinations of characters, such as a totalizer of an adding machine. Timer 20 has an input lead from drive motor 25 to synchronize its operation with the revolution of shaft 3.

The number of home positions of gear 5 equal 11 in the ratio n/m; thus, if the tooth ratio between sun gear 5 and planet gear 7 were increased to 2:1, the gear 5 would have only two home positions and the wheel 8 would carry a single set of type faces.

It will be noted that the printing wheels 8 are cupshaped and envelop the associated pinions 7 as well as the toothed portions 5" of the corresponding ring gears 5, thereby aifording a particularly compact construction. Details of the selector arrangement 9, 10, 2024 may be varied and the structure of the planetary gears may also be altered to suit specific requirements; the number of printing stages, of course, can be chosen at will. Other, similar machines can be driven in tandem with the illustrated device from the same shaft 13', 3, 13".

I claim:

1. In a printer, in combination:

a ring gear mounted for rotation about an axis;

a planet gear in mesh with said ring gear;

a planet carrier supporting said planet gear eccentrically to said axis;

drive means for rotating said planet carrier about said axis whereby said planet gear revolves in an orbit centered on said axis while rolling on the inner periphery of said ring gear;

a printing wheel rigid and coaxial with said planet gear, said wheel carrying a plurality of angularly spaced type faces on the outer periphery thereof;

a printing platen confronting said printing wheel for contact with respective type faces thereof in different angular positions of said ring gear, each of said angular positions determining the cycloidal motion of a respective type face toward and away from said platen upon rotation of said planet carrier about said axis;

a frictional coupling between said planet carrier and said ring gear for entraining the latter upon rotation of the former;

and stop means actuatable upon each revolution of said planet gear for selectively arresting said ring gear in any one of said different angular positions.

2. The combination defined in claim 1 wherein said ring gear and said planet gear have a tooth ratio of mm, n and in being integers, further comprising releasable detent means normally arresting said ring gear in any one of 21 home positions, said wheel having a peripheral portion free from type faces confronting said platen in any of said home positions of said ring gear.

3. The combination defined in claim 2 wherein m is greater than 1 and said wheel has In identical sets of type faces, corresponding type faces of said sets being spaced apart by 21r/m radians.

4. The combination defined in claim 3 wherein 11:3 and m=2.

5. The combination defined in claim 1 wherein said planet carrier comprises an eccentric shaft parallel to said axis, said frictional coupling including a disk keyed to said shaft and centered on said axis adjacent said ring gear.

6. The combination defined in claim 5 wherein said frictional coupling further includes a corrugated spring washer interposed between said disk and said ring gear.

'7. The combination defined in claim 5 wherein said ring gear, said disk, said planet gear and said wheel are duplicated in a plurality of longitudinally spaced positions alongsaid shaft.

8. The combination defined in claim 7, further comprising a cylindrical housing open toward said platen and centered on said axis, said ring gears, disks, planet gear and wheels being substantially completely received in said housing.

9. The combination defined in claim 8 wherein said wheels are cup-shaped members enveloping the corresponding planet gear and part of the corersponding ring gears.

10. In a printer, in combination:

a plurality of ring gears juxtaposed for independent rotation about a common axis;

a plurality of planet gears each meshing with a respective ring gear;

a common planet carrier supporting said planet gears eccentrically to said axis and in mutual axial alignment;

drive means for rotating said planet carrier about said axis whereby said planet gears revolve in orbits centered on said axis while rolling on the inner peripheries of the associated ring gears;

a plurality of printing wheels each rigid and coaxial with a respective planet gear, each of said wheels carrying a plurality of angularly spaced type faces on the outer periphery thereof;

a printing platen confronting said printing wheels for concurrent contact with respective type faces thereof in any of several different angular positions of the associated ring gears, each of said angular positions determining the cycloidal motion of a respective type face of the corresponding printing wheel toward and away from said platen upon rotation of said planet carrier about said axis;

and individual selector means for said ring gears independently operable upon each revolution of the respective planet gears to vary the angular position of each ring gear for successive orbital revolutions.

11. The combination defined in claim 10 wherein said selector means comprises a frictional coupling between said planet carrier and each ring gear and stop means engageable with each ring gear in said different positions thereof.

References Cited UNITED STATES PATENTS WILLIAM B. PENN, Primary Examiner 

